Rac crs Resource VIP

Rac crs Resource VIP each node has a VIP, which is the IP address we access. If a node goes down, its VIP address will be moved to another node according to the algorithm, www.2cto.com seems to be a normal access for users. I think the vip is used for failover. When node a fails, the vip will be moved to Node B, but Node B does not listen on this vip address, so that the client can quickly know that node a is down, if you switch to Node B using the traditional TCP timeout, it will take a long time. If you want to implement failover, it will be in tnsnames. the relevant configuration must be provided in ora. (1) TCP/IP protocol stack timeout. Logically, the TCP/IP protocol stack is the TCP protocol for communication between the same layer, provides integrity services for data transmission. That is, after receiving data packets, the transport layer of the receiving end must return a confirmation message to the transport layer of the sending end. If the sender does not receive the confirmation message within the specified time period, the sender determines that the package is lost and resends the message. If no response is received after multiple resends, the transmission layer of the sending end knows that the network is faulty, terminates the sending attempt, and notifies the application layer. For example, if user_A uses sqlplus to connect to the oracle server, sqlplus will throw a connection error. The client connection request must wait until the transmission layer times out, the database server or listener has a problem. Suppose there is a 2-node RAC environment, VIP1 VIP2, And now node 2 has a fault: ① After CRS detects a node 2 exception, trigger clusterware reconstruction, kick out node 2 ② VIP2 and drift to node 1 www.2cto.com ③ the user's connection request to VIP2 will be routed to node 1 by the network layer ④ because node 1 has VIP2, therefore, the data packet will pass through the network access layer, network layer, and transmission layer ⑤, but the listener on node 1 only listens to VIP1 and public IP, and does not listen to VIP2, that is, no corresponding program at the application layer receives this package. 6 The client can immediately receive this error, then the client will initiate a connection to VIP1 again (ii) VIP Drift Problem VIP only drifting out of the VIP when the system fails If you do not return, you can use crs_relocate to pull the vip "back". This is a feature, and the VIP does not automatically return failover to prevent secondary brown out, But 10.2.0.3 is an exception. This parameter is enabled by default, other versions are disabled by default. Ora_racg_vip_failback = 0 we can use v $ session. failed_over is YES, indicating drifting or crsd. the listener does not automatically register after the log outputs the vip drift. It only reduces the length of the failover time when the connection is established. The objective of the listener drift is to return an error faster when the connection is established, rather than the tns timeout. (3) The VIP name in the vip configuration hosts file is recommended to be named hostname-vip below. The hostname-priv name should not be underlined. Dashes okay (iv) TAF (Transparent Application Failover) Oracle's TAF is actually built on the VIP technology. If you want Transparent Application Failover, you must configure the TAF Application policy. If the TAF policy is configured, although the client receives an error, the TAF configuration will immediately try the connection of the next node. In this way, the application implements a truly transparent failover, it also reduces the waiting time of client users. If you do not use the vip connection, vip1 will automatically switch to node2. however, the client that has been connected cannot immediately know that node 1 is actually working, therefore, clients that have been connected to the actual node will constantly try to connect to the next address in tnsname until the connection times out. Therefore, this switchover takes a long time, the client can switch to node2. (v) the difference between the IP address and the VIP address ① the VIP address is floating, while the IP address is fixed ② the IP address uses the transport layer to time out, the VIP uses the application layer to immediately respond to the ③ IP address for non-connected connections, while the VIP allows connected connections to continue